1. Field of the Invention
The present invention relates to a semiconductor wafer processing apparatus having a cushion function, which is used in manufacturing processes for semiconductor devices, electronic parts and related products, or optical disks etc. The semiconductor wafer processing apparatus receives a semiconductor wafer (which will be simply referred to as a wafer hereinafter) from a clean box that stores the wafer and performs processing of the wafer with a collision avoidance function.
2. Description of Related Art
Manufacturing of wafers, which are used for semiconductor devices etc., must be performed under a condition in which a high degree of cleanness is ensured. Therefore, manufacturing of wafers was generally performed in a clean room the whole interior of which is kept in a highly clean condition. However construction and maintenance of a large clean room with a high degree of cleanness require a significant initial investment and service costs. In addition, even if once a plant investment is made for such a clean room, a modification of the layout of the room might be required later due to a modification in the manufacturing process, which would require a large additional investment. Therefore, use of clean rooms is uneconomical. In view of the above-described situation, recently a certain method has been widely adopted, that is, to keep a high degree of cleanness not within the whole interior space of a room but only within a small environmental space (which will be referred to as a mini-environment) inside a processing apparatus to attain the effects same as those obtained by keeping a high degree of cleanness within the whole of the room. (In the following, a processing apparatus that adopts this method will be called a semiconductor wafer processing apparatus.)
Specifically, semiconductor wafer processing apparatus as shown in FIG. 1 are arranged in a manufacturing room. When the door 3 of the semiconductor wafer processing apparatus 10 is in a closed state, a mini-environment portion 5 in which processing of a wafer is performed is kept in a highly clean condition. Wafers 7 are transferred from one semiconductor wafer processing apparatus to another using a wafer storing container hermetically closed by a lid 4, whereby the interior of the container is kept in a highly clean condition. This wafer storing container is composed of a box body in the form of a housing and the lid 4. This container will be referred to as a clean box 6 hereinafter. The wafers 7 having been delivered to a semiconductor wafer processing apparatus by the clean box 6 is subjected to further transportation in the interior of the semiconductor wafer processing apparatus. The mini-environment portion 5 is provided with a window opening 2 that functions as an access opening through which wafers 7 are to be transferred into the mini-environment portion 5. The opening 2 is closed by the door 3 that is provided in the interior of the mini-environment portion 5. The door 3 is provided with a holding means for holding the lid 4, such as suction means or a latch mechanism etc.
The clean box 6 having been delivered to the semiconductor wafer processing apparatus is placed on a docking plate 12 with the lid 4 of the box facing toward the window opening 2 of the mini-environment portion 5. Then the docking plate 12 is moved (in the right direction in FIG. 1) so that the clean box 6 is brought to a position (which will be referred to as a prescribed position hereinafter) close to the window opening 2 provided on the semiconductor wafer processing apparatus 10 and stopped. After-the clean box 6 is stopped at the prescribed position, the lid 4 is held by the door 3 and brought into the interior of the mini-environment portion 5 with the door 3. Thus, the lid 4 is detached from the clean box 6 and the window opening 2 is made open. The wafers 7 stored in the clean box 6 are transferred into the semiconductor wafer processing apparatus 10 through the window opening 2 that has been made open. Thus, the space to which the wafers are exposed can be always kept highly clean without a need for establishing a highly clean condition within the whole interior of the manufacturing room. Therefore, this method realizes the effects same as those attained by establishing a clean room condition within the whole of the room, and so it is possible to reduce construction and maintenance costs to realize an effective manufacturing process.
In this semiconductor wafer processing apparatus 10, the clean box 6 is generally manufactured in accordance with a standard. In other words, the shape, size and weight of the clean box 6 are standardized, so that the clean box 6 can be used in a plurality of semiconductor processing apparatus 10 without changing the specification of the clean box 6.
On the other hand, Japanese Patent Application No. 2000-262472 discloses a semiconductor wafer processing apparatus having a dust proof function. In the wafer processing apparatus disclosed in that application, a clean box is not in contact with the wall of a mini-environment portion, and small clearance is formed between the mini-environment portion and the clean box.
The clean box is generally manufactured by molding using a reinforced plastic in accordance with the above-mentioned standard. In that standard, a reference length that is designated by numeral 11 in FIG. 1 with respect to the opening side end of the clean box is determined in reference to the center of the clean box.
However, even if the clean box is molded in accordance with the standard, size range by a manufacturing errors in molding. In addition, there are minor differences between manufacturers in their interpretations of the standard length 11 that is defined as the length between the center of the clean box 6 and the opening side end of the clean box 6. Those differences includes, for example, whether the width of the flange portion is to be included in the reference length or not. Therefore, there are variations in the size of actually manufactured clean boxes 6, which cause various problems as follows.
In the following, the problems will be described with reference to FIGS. 4A to 4C.
FIGS. 4A to 4C are schematic drawing showing a portion of the equipment shown in FIG. 1, in which a portion including the clean box 6 is illustrated in an enlarged manner. In these drawings, the exaggeration is made in order to specifically illustrate the above-mentioned problems.
For example, FIG. 4A shows a case in which the reference length 11 of the manufactured clean box 6 is too short. In this case, when the docking plate 12 is stopped at a prescribed position, the lid 4 is not in contact with the door 3. In the case shown in FIG. 4A, there is a problem that a holding means 8 does not operate normally and the door 3 cannot hold the lid 4 appropriately, since the lid 4 and the door 3 cannot be in contact with each other.
FIG. 4B shows a case that is contrary to the case show in FIG. 4A, namely FIG. 4B shows a case in which the reference length 11 is too long. In this case, the surface, of the clean box 6 would collide with the wall of the semiconductor processing apparatus 10 before the docking plate 12 reaches the prescribed position. The collision might result in damaging of the clean box 6 or damaging of the semiconductor wafer processing apparatus, 10, or trouble of the docking plate 12, which is a problem.
FIG. 4C shows a case in which the lid 4 is too thick. In this case, the lid 4 abuts the door 3 before the movement of the docking plate 12 is completed. Since conventional driving devices for moving the docking plate 12 use a motor, the driving of the docking plate 12 continue after that. However, if the motor continues to drive the docking plate 12 in spite that the movement of the clean box 6 is blocked by the door 3, an excessive load that can damage the motor is exerted on the motor, which is a problem.